A network device may facilitate an exchange of information in accordance with a network protocol. For example, a network device may transmit and/or receive 52-byte cells of Asynchronous Transfer Mode (ATM) information between the physical layer (PHY) and upper layers in accordance with the Universal Test and Operations PHY Interface for ATM (UTOPIA) interface as defined in ATM Forum document AF-PHY-0017.000 entitled “UTOPIA Specification Level 1, Version 2.01” (March 1994).
Similarly, a network device may transmit and/or receive packets of information, such as variable size Internet Protocol (IP) packets in accordance with a System Packet Interface (SPI) as defined in ATM Forum document AF-PHY-0143.000 entitled “Frame-Based ATM Interface (Level 3)” (March 2000) or in Optical Internetworking Forum document OIF-SP13-01.0 entitled “System Packet Interface Level 3 (SPI-3): OC-48 System Interface for Physical and Link Layer Devices” (June 2000). Moreover, Synchronous Optical Network (SONET) technology may be used to transport IP packets in accordance with the Packets Overt SONET (POS) communication standard as specified in the Internet Engineering Task Force (IETF) Request For Comment (RFC) 1662 entitled “Point to Point Protocol (PPP) in High-level Data Link Control (HDLC)-like Framing” (July 1994) and RFC 2615 entitled “PPP over SONET/Synchronous Digital Hierarchy (SDH)” (June 1999).
By way of example, a network device may receive ATM cells or POS packets via a receive (Rx) network line and transmit the information to a network processor. The network device may also receive ATM cells or POS packets from the network processor and transmit the information via a transmission (Tx) network line. In either case, the interface between the network device and the network processor may have one of a number of different widths (e.g., the interface may have either a 8, 16, 32, or 64-bit width).
Typically, the network device includes circuitry designed to handle a particular network protocol (e.g., ATM cells or POS packets) and/or interface width and rate. Such an approach, however, may not be practical if the network device will support multiple network protocols and/or interface widths (e.g., the network device may need separate circuitry to implement each network protocol and interface width).